Wk 3- Epithelial Tissue & The Integument
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The integumentary system The I. System is comprised of 1. C- membrane = the Epi- and D? • Accessory structures = hair, ? exo- glands
Cutaneous membrane - epidermis and dermis nails, exocrine glands
Epidermis The epidermis = - - - epithelium Epidermis is made up of 4 cells and 5 layers
Keratinised stratified squamous
Epidermis cells: • Keratinocytes: tough fibrous protein, -0% epidermis • Melanocytes: pigment m?, 8% epidermis ( protect from - -) • Intraepidermal macrophages: I? cells • Tactile epithelial cells: form sensory structures
• 90% • Melanin , 8% UV • Immune
Epidermis layers • Stratum basale: single base layer of cuboidal /columnar cells. Contains germination cells to produce more k? • Stratum spinosum: spiny appearance, contains - to 10 layers of k? • Stratum granulosum: - to 5 flattened layers of k?transitioning live to dead (apoptosis) • Stratum lucidum: 4 to 6 layers clear, flat, dead k? • Stratum corneum: surface layer of 25 to -0 layers dead, flat k? shedding and r?
• keratinocytes • 8, keratinocytes • 3-5 , keratinocytes • keratinocytes • 25 - 30 , keratinocytes , replacing
The Dermis The dermis is divided into 2 layers • Papillary : l? connective tissue = replacing • Reticular: d? connective tissue= stable base
Loose Dense
The Dermis consists of; Collagen fibres: strong and - stretching Elastic fibres: permit - and recoil Epidermal pigments: carotene orange/yellow and melanin (brown to -) made by melanocytes
resist Stretching black
Epithelial cells Epithelial cells must maintain structure to function well Their epithelial function is either to ; • Cover and l? (selectively permeable barrier to protect and cushion) • G? (secret)
• line 2. Glandular
Epithelial cells Epithelial cells are tightly connected by 1 of 3 junctions. • Tight junctions: fusion / st? of cells together • Desmosomes: sticky - pads together • Gap junctions: riveted cells allowing tiny - through
• stitch • Velcro • ions
Epithelial cells Epithelial contain 1. Germinative cells: used in cell division to produce cells 2. Gland cells: exocrine (secrete - surface) Endocrine (secrete - bloodstream) The pancreas produces exo- gland cells (digestive enzymes) and releases endo- gland cells (hormones in bloodstream)
• Onto , into , exocrine ,endocrine
Epithelial cells Epithelial cells are 1 of 3 shapes 1. Flat/thin: ? 2. Cubes: ? 3. Long columns: ? These shaped cells will always sit on top of a basement membrane
• Squamous • Cuboidal • Columnar
Epithelial cells Epithelial cells are classified into 2 layers; • Simple single layer Squamous: for diffusion and ab? Cuboidal: for secretion and ab? Columnar: self cleansing for ? and ab? • Stratified multiple layers Squamous : stronger structure to - stresses
Squamous: diffusion and absorption Cuboidal: absorption Columnar: secretion and absorption 2. Resist
Accessory structures Hair - insulate , provide sen? information on - surface Nails- tightly packed - epidermal cells, protect ends of fingers / toes
Sensory , Skin Keratinised
Cell junctions What are the 3 types of cell junctions ? • T? Junctions (fusion of cell membrane) • D? (Molecular Velcro ) • G? (Special structures allow passage of ions)
Tight junctions Desmosomes Gap junctions
Gland cells ? Gland cells Release secretions ? surface of cell (sweat) ? Gland cells Release secretion ? interstitual fluid (hormones)
Exocrine, onto Endocrine, into
What are the 5 Functions of epithelium: • P? =Barrier to mechanical /chemical/ biological attack • Excretion= Water/ salts /waste products • H? =Body temperature control via insulation/evaporation • Manufacture= Contributes to synthesis vitamin D • S? =Touch /pressure /temperature
Protection Excretion Homeostasis Sensation